1. Field of the Invention
This invention relates generally to locksets employed to secure doors and electro-mechanical assemblies that permit locksets to be electrically locked and unlocked. More particularly, the present invention relates generally to a mortise-type lockset that incorporates an internal selectively engageable electro-mechanical clutch assembly.
2. Description of the Related Art
Locksets that incorporate a lockable latch and/or dead bolt have long been incorporated into doors. Electronic security systems for controlling access through doors are also common. Electronic security systems typically control access through doors incorporating mechanical locksets by selectively engaging the rotatable operator (usually a lever or knob) on the unsecured or outside side of the door. This has been accomplished by means of an electromechanical clutch mounted between the operator and the lockset. A properly activated clutch mechanically couples the operator to the lockset and permits rotation of the operator to retract the latch and allow entry through the door.
An example of this type of clutch may be found in U.S. Pat. No. 5,640,863. Such separate, add on clutches work well and have the advantage of being compatible with existing locksets, allowing existing key-based security systems to be retrofitted with electronic security capabilities. For new installations where electronic security systems will be installed or are contemplated, however, the separate installation and mechanical coupling of discrete clutches and locksets have proven to be awkward and time consuming. Separate clutch and lockset assemblies require a volume of installation space not always available in a given application. Additionally, designers may be constrained by the need to provide space for the necessary components.
Locksets used to control access through frequently used doors typically incorporate a beveled latch and a spring for biasing the latch in the projected or latched position. Such self-latching locksets have the advantage of automatically latching the door when it is closed, and with certain lock mechanisms, automatically locking the door. The beveled, spring biased latches employed in self-latching locksets have the disadvantage of being susceptible to tampering that may result in unauthorized entry. In many installations, tools or other slim objects can be slipped between the door and the doorframe to engage the beveled edge of the latch and force the latch into a retracted position, thereby allowing the door to be opened.
Dead bolts have been employed to overcome some of these deficiencies. Dead bolts typically have a squared off end which is not susceptible to tampering. Dead bolts also typically have a longer throw and are not spring biased, therefore maintaining the dead bolt in an extended position until the lock mechanism is employed to retract it. A major deficiency of dead bolts is that they must typically be manually engaged. Manual engagement is inconvenient for a door that is frequently used.
There is a need in the art for a lockset which provides the strength and tamper resistance of a dead bolt with the convenience and dexterity of an electrically lockable self-latching lockset.
Briefly stated, a preferred embodiment of the mortise lockset with internal clutch includes a self-latching autobolt and an electrically actuated coupling that permits retraction of the autobolt by the operator on the unsecured side of the door. A key actuation mechanism allows the lockset to be operated as a conventional key-based security system or operated in conjunction with an electronic security system.
The autobolt or self-latching dead bolt is spring biased toward a projected or latched position. A retraction lever is engaged with the autobolt and is pivotable by a key operated retraction cam or rotational movement produced by operators (levers or knobs) located on the secured and unsecured side of the door. Pivoting of the retraction lever overcomes the spring bias, resulting in retraction of the autobolt. Operators on the secured and unsecured sides of the door are connected to inside and outside cams in the lockset, respectively, for rotation therewith. The inside cam, located adjacent the secured side (inside) of the door, is continuously coupled to the retraction lever, allowing rotation of the operator to pivot the retraction lever and retract the autobolt. The outside cam, located adjacent the unsecured side (outside) of the door, is selectively coupled with the retraction lever. The inside and outside cams are positioned on either side of the retraction lever at the retraction lever pivot point. The inside cam, outside cam and retraction lever share a common axis of rotation.
Entry from the unsecured side of the door may be obtained either by actuating the electro-mechanical coupling between the outside cam and the retraction lever, or using a key to rotate the retraction cam. The electrically actuated coupling (clutch assembly) incorporates a motor which, by moving an injector and an injector arm, exerts force on a locking piece, resulting in rotational engagement of the outside cam to the retraction lever.
The locking piece is movably secured for rotation with the retraction lever by a pin and is spring biased toward a locked position in which the locking piece is disengaged from the outside cam. A convex head on the pin is slidably engaged along an arcuate surface of the pivotable injector arm. The injector arm is disposed between the pinhead and an axially movable injector. A rounded corner of the injector slidably engages a ramp on the injector arm, whereby the injector arm can be moved toward the clutch assembly by the injector. A coil spring drive shaft connects the injector to the motor such that rotation of the drive shaft moves the injector along an axis.
Rotation of the drive shaft in a first direction moves the rounded corner of the injector along the ramp of the injector arm, pivoting the injector arm to overcome the spring bias on the locking piece and force the locking piece into an unlocked position. In an unlocked position, the locking piece is engaged with the outside cam. Rotation of the drive shaft in a second direction moves the rounded corner of the injector in the opposite direction along the ramp of the injector arm, allowing the injector arm to be moved away from the clutch assembly by the spring bias on the locking piece. A locked position is achieved when the locking piece is disengaged from the outside cam. When the locking piece is in the locked position, the outside cam rotates independently of the retraction lever and rotation of the operator located on the unsecured side of the door will not retract the latch.
An autobolt assembly in accordance with the present invention includes a roller captured within a squared-off projectable end of the bolt. The roller is positioned so that a portion of the roller protrudes from the outer end face of the bolt. A projectable bi-beveled auxiliary latch and associated pivotable hook restrain the bolt in a retracted position in which only the roller protrudes from the latch edge of the door. The auxiliary latch is spring biased toward a projected position in which the auxiliary latch acts to pivot the hook into engagement with a notch in the bolt, restraining the bolt in the retracted position. A closing door causes the auxiliary latch to be forced into a retracted position in which the auxiliary latch acts to pivot the hook away from engagement with the bolt, releasing the bolt from its retracted position.
Upon release, the spring biased bolt moves toward a projected position causing the roller in the end face of the bolt to contact the strike plate. The roller rotates freely, allowing the bolt to move over the strike plate until the bolt is aligned with the latch opening in the strike plate, at which time the bolt projects fully into a latched position in the latch opening. Retracting the bolt and opening the door allows the auxiliary latch to re-assume its projected position, causing the hook to restrain the bolt in a retracted position until the door closes, thereby bringing the auxiliary latch into contact with the strike plate once again.
In a further embodiment in accordance with the invention, the bolt is locked in the projected position, ensuring that only the retraction lever can retract the bolt. A pivoting lock bar is spring biased toward a position in which the lock bar engages the rear or inner end of the projected bolt to prevent the bolt from being moved to the retracted position. The lock bar has a cam surface, which cooperates with a protrusion on the retraction lever. Movement of the retraction lever to retract the bolt also moves the lock bar to a position where the lock bar does not interfere with retraction of the bolt. The lock bar prevents potential unauthorized entry by maintaining the latch bolt in the projected position despite the presence of a countering force applied by a tool or other object. The lock bar is inaccessible to a burglar and can be disengaged only by movement of the retraction lever.
A further alternative embodiment combines the electrically actuated clutch assembly with a more conventional self-latching mortise lockset.
An object of the present invention is to provide a new and improved lockset that incorporates an internal electrically actuated clutch mechanism.
Another object of the present invention is to provide a new and improved lockset that is self-latching but includes the security advantages of a dead bolt.
A further object of the present invention is to provide a new and improved lockset that may be incorporated into either a standard key-based access control system or an electronic access control system.
These and other objects, features, and advantages of the invention will become readily apparent to those skilled in the art upon reading the description of the preferred embodiments, in conjunction with the accompanying drawings.